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Feasibility Evaluation of the Arkansas Valley Pipeline <br />Water Works! Committee <br />June 2003 <br />In the case of a water right for direct diversion from a stream, it is understood that under <br />Colorado water law, the right of direct diversion cannot be constrained by water quality <br />effects resulting from the direct diversion, i.e., the water can be diverted without concern for <br />water quality effects. The right of exchange, however, differs from the right to make a direct <br />diversion. Colorado water law states that, in cases of exchange, downstream water users are <br />entitled to a quality of water for which they were used to before the exchange. This is one of <br />the issues that could be clarified by a decision in the Denver Water v. Thornton cases. <br />The water attorney for the City of Aurora was contacted concerning whether there had been <br />objections based on water quality to any of Aurora's pending exchange cases. The response <br />was that there were objections filed to Aurora's pending exchange cases based on water <br />quality. The attorney indicated that these objections were not viewed as a serious obstacle to <br />obtaining a decree for the right of exchange and he expected to reach a settlement on these <br />objections. <br />The 303(d) listing of the lower Arkansas River as only partially supporting the designated <br />uses for specific reaches due to high levels of selenium, iron, and sulfate could also be an <br />obstacle for the proposed exchange of 4,300 ac-ft to Pueblo Reservoir. The Water Quality <br />Control Division may determine that the reduction of dilution flows caused by the exchange <br />could result in an increase in concentration of the constituents of concern (i.e., selenium, <br />iron, and sulfate) and thus impede any progress toward developing site-specific, use <br />supporting criteria, and a Total Maximum Daily Load, as required by the Clean Water Act. <br />Forecasting the likelihood of the Water Quality Control Division pursuing this course of <br />action is beyond the scope of this analysis. <br />In order to determine the likelihood of potential objections to the exchange scenario, a <br />preliminary analysis of effects of the exchange on water quality was performed. Results of <br />the analysis estimate that increases in average monthly TDS concentration could vary from a <br />maximum increase in TDS concentration at LaJunta of 4.8 percent in April to 1.3 percent in <br />June as a result of the exchange and/or substitution of an average of 6,000 ac-ft per year. <br />Similar results are presented for the USGS gaging station upstream from the City of Pueblo, <br />which indicate that average monthly TDS loads at that location would increase by 1 to Z <br />percent as a result of the proposed exchange/substitution. <br />Colorado Springs Utilities commissioned Brown & Caldwell to develop a preliminary <br />characterization of selenium throughout the lower Arkansas River watershed. The report that <br />documents this characterization was finalized in January 2000. This report states that the <br />reach of the Arkansas River from Pueblo Reservoir to John Martin Reservoir is a complex <br />water system with multiple inflows and outflows contributing to numerous gains and losses <br />of selenium from the system. It is apparent from this report that selenium, and it can be <br />assumed iron and sulfate as well, are introduced to the river along the entire reach mainly <br />24 <br />GEI Consultants, Inc. <br />01284 03-06-30 Feasibility Evaluation Final <br />